import java.util.Scanner;

public class Main1460 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        double x= sc.nextDouble();
        double n=0;
        int a=0;
        double m=2;
        while (n<x){
           n=n+m;
           m=m*0.98;
           a++;
        }
        System.out.println(a);
    }
}
